Method of making composite plastic lined metal pipe



May 4, 1948. c. G. MUNGER 2,440,725

METHOD OF MAKING COMPOSITE PLASTIC LINED METAL PIPE.

Filed Sept. 4, 1944 6' STEEL PIPE 10;, PLASTIC runs COATED WITH ADHESIVE PDPE HEATED BY RING BURNER 0/4245? 6'. MAME-E, v INVENTOR.

Patented May 4, 19 48 r METHOD OF MAKING COMPOSITE PLASTIC LINED METAL PIPE Charles G. Manger, San Gabriel, CaliL, assignor to American Pipe andConsil-uctlon 00., a corporation oi Delaware Application September 4, 1944, Serial No. 552,624

of the type wherein atube of Claims.

The present invention relates to the method of making a composite plastic lined metal pipe bonded to the interior of the pipe.

to be used under certain conditions in which the more impervious to water and chemicals and composite pipe is subjected to heat, it will be understood that plasti'coi may be used.

the'thcrmosetting type plastic material is thus be completely inert, it is desirable that in -making the plastic, the plastic have combined therewith pigments or plasticisors or both. i The 7 Composite pipes ofthe type herein described 5 use 01' such materials in plastic is well known are of extremely wide use. For instance, they and it is to be understood that whenthe term are particularly desirable for conveying chemi- "plastic is used herein it isnot necessarily lim-v cals or food products, so that such substances ited to such compositions but is intended to inare kept free from contamination by the iron clude all such materials as synthetic and natural o'riother metal of the pipe. In the case of chem resins, polymers and elastomers. V 1 icals such as caustic, acids of all kinds, and cor- Other objects and advantages will appear hererosive salts, the plastic lining keeps the pipe en'- inafter from the following description and drawtirely free from contact with the chemicals. This' ings. I is an essential in the chemical and allied indus- Referring to the drawings, which are for detries. As jurther illustrations, the composite scriptive purposes only: pipe of my invention m y b u in h W n Fig. 1 is a side perspective view of a length industry for conveying wine throughout the oi steel pipe such as is used in making the comwinery protected from anycontamination from. posite pipe of the present invention: the iron or other metal of which the pipe may Fig. 2 is a view similar to Fig. 1, illustrating be made, and it is apparent that the composite a step of the method consisting of sandblasting pipe may be used for brandies and distilled the interior of the steel pipe: qu rs nd in the milk i y and in other ig. 3 isa perspective view ofalength of plastic food industries where contamination is to be tub uch as may be used in producing the cornavoided. V posite pipe of this invention;

The method of this invention, while useable Fi 4 is a, vi w similar to Fig. 3, showing the for any size pipe, is particularly adaptable for plastic pipe oated with adhesive; the production of small pipe as, for instance, one- Fi 5 is an enlarged fragmentary longitudinal h f t n in p p a t i t necessary o inr sectional view of a length of metal pipe with a sert any mechanism into the interior f the P p plastic tube therein, illustrating the manner of during the operation. closing the end of the tube;

. It i an O je of t is nv n i n to Provide a Fig. 6 is a side elevation of the-unit shown simple and e en mical method of makin a in Fig. 5 diagrammatically illustrating a support Desite P p consisting m l With a lining e for the unit as the unit extends through a ring f pl c m e l burner and illustrating the expanding or the It is a further object of this invent n t p -l tube and forcing of the air from between the tube vide a simple andeconomical method of making d pipe; d a. composite plastic lined metal pipe in which Fig. 7 is a perspective view of a finished comthe plastic is completely bonded to the interior poslte m t d' t pipe made according of the metal pipe throughout its length witht thi j nflon out any unbonded areas caused by bubbles of It isfto be understood that the drawings are air between the plastic and th m merely diagrammatic [for illustrative purposes T Di ics u ed f9 making the tubular linand the method of the present invention described in of the metal pipe are prefer y 0 the therin connection therewith is as follows. m last t per ut when th m site ipe is The method of producing the composite pipe herein referred to is as follows: The inside ofthe metal. pipe 8 is preferably cleaned as, for instance, as shown inFig. 2 by sandblasting the inside 01 the pipe with a nozzle indicated at 9. For the purpose .of making the plastic tube 59 or by dipping the pipe in a standard pickling bath as, for-instance.

when the pipe is of" steel the bath should preferably consist of hot sulphuric acid and should the steel pipe be etched as just referred to it is preferable to passivate the steel to prevent it from rusting prior to the installation of theplastic tube or linensuch as is done by dipping the pipein a phospheric acid- I chromic acid solution followed by washing and drying. I

After the steel pipe, indicated at a on the draw ings,has been etched or otherwise cleaned asv above described, a plastic tube such as indicated at I of slightly smaller diameter than the in- I terior diameter of the steel pipe is covered with an adhesive indicated at H. The plastic tube,

which is preferably longer than the pipe, is placed within thepipe as shown in Fig. 5, the ends of the tube extending beyond the ends of the pipe al though it should be understood that the plastic tube'may be of the same length or'even somewhat shorter than the pipe.

as used herein is inclusive of any plastic tube whether of the extruded type, or seamed type. The next step is the closing of the ends oi the plastic tube. This is done by means-oi plugs in-.

dlcated at I! which fit into the'ends oi the plastic tube and which may be of any desired material that will hold pressure butpreierably steel or some similar metal. I The ends or the plastic tube are' clamped around the plu s I2 by means of yieldable bands indicated at It and which firmly seal the ends 01' the tube about the plugs. A pipe indicated at ll is sealed'in one oi" the plugs l2 for the introduction of fluid pressure into the tube from any suitable pressure source (not shown). I

It'is preferable, although not necessary, to support the plastic tube in the-pipe in spaced relation to the interior of the metal pipe and to accomplish this 1 preferably use a band indicated at I! which is clamped about the pipe 8 near its end, such band I! having an arm or bracket indicated' at I! extending beyond the end of the pipe I and beyond the end of the plastic tube ll terthe outer or exposed end of the plugs l2- The unit consisting of the steel pipe, plastic tube, etc., as shown in Fig. 5, is then passed bodily through a limited heating zone as shown in Fig. 6. In the form shown, this heating zone is produced by a circular gas burner indicated at 20. Merely as an example, I have found that with common forms of plastics oi the vinyl type resins temperatures from 200 F. to 300 F. are sufllcient but it is to be understood that the degree oi heat necessary will vary with different plastic materials. For the purpose of passing the unit through the heating zone I have shown the unit supported on a series of rollers indicated at II but it is to be understood that any other form of support which will support the unit and permit the unit to be moved horizontally through the heating zone may be used.

While I have shown a circular gas burner indicated at 20, it is to be understood that any form of heating apparatus, such as, for instance, an induction coil, may be used so long as the heating element produces a limited heating zone which extends entirely around the unit. v

It is to be understood that the fluid pressure such as hydraulic or air is maintained inside the plastic tube during the heating operation and as the unit moves through the heating zone as, ior instance, in the direction of the arrow shown The term "tube" I has been moved through the heating zone a comminating in a ring indicated at I! which receives 4 I and expands metal pipe. This expanding movement of. the

plastic tube may be likenedto a waveindicated in dotted lines at 25 in Fig. ,6 which, as the tube expands, forces any air between the tube-and the pipe to be squeezed ahead of the wave and out oi the end of the unit sothat when the pipe is finished no air bubbles remain between the tube and the pipe. I

It will be understood that after-the entire unit posite plastic lined metal pipe is produced oithe character shown diagram'maticallyin Fig. 7, it being understood thataiter the passing of the unit through the heating zone has been completed the plugs l2 and supporting structure for the plugs are removed.

,While I have illustrated and described a specific method of producing a composite plastic lined metal pipe, it is to be understood that I do not limit my invention to the particular detailsshown and described butintend to cover such modifica tions as come within'the appended claims.

. I claim as my invention: 7

1; The method oi making a composite plastic lined metal pipe which comprises: coating the outside of a plastic tube with adhesive; inserting the coated tube into the'pipe; the tube being of slightly smaller diameter than the inside diameter of the pipe and providing a space there-'- between open to atmosphere; closing the endsof the plastic tube; introducing fluid under pressure into the tube and passing the pipe with the tube therein, while under pressure, progressively longitudinally through a heating zone.

2. The method of making a composite plasticlined metal pipe which comprises: coating the outside oi a plastic tube with adhesive; inserting slightly smaller diameter than the inside diameter of the pipe and providing a space therebetween open to atmosphere; closing the ends of the plastic tube; introducing fluid under pressure into the tube and passing the pipe with the tube therein, while under pressure, axially through a heating zone oi limited extent surrounding the pipe. i

3. The method of making a composite plastic lined metal pipe which comprises: inserting a plastic tube intothe pipe; the tube being of slightly smaller diameter than the inside diameter of the pipe and providing a space therebetween open to atmosphere; closing the ends of the plastic tube; introducing fluid under pressure into the tube and passing the pipe with the tube therein, while under-pressure, progressively longitudinally through a heating zone.

4. The method of making a compositeplastic lined metal pipe which comprises: coating the outside of a plastic tube with adhesive; inserting the coated tube into the pipe; thev tube being oi slightly smaller diameterthan the inside diame-.

the air between the pipe and tube ahead of the I heated portion. I

5. The method of making a composite plastic lined metal pipe which comprises: providing a metal pipe and a plastic lining tube, the latter having a lesser external diameter than the internal diameter of the pipe; coating the outer surface of the tube with adhesive; inserting the tube in the pipe and maintaining the same in spaced relation to the inner surface of the pipe; inflating said tube; and expanding said tube into contact with the pipe progressively axially thereof by subjecting the pipe to heat progressively axially thereof while maintaining the tube inflated.

CHARI-JES G. MUNGER.

nnrnanncns men The following references are of record in the file of this patent:

UNITED sums m'mms Number Number Name Date Bergier Feb. 5, 1901 Kueppers Apr. 22, 1919 Kueppers Nov. 1, 1921 Wachowitz Apr. 22, 1930 Currie Jan-14, 1936 Schnabel May 30, 19:39 Stahl Feb. 29, 194.4v Munger Mar. 25, 1947 Peterson July 15, 1947 FOREIGN PATENTS Country Date Great Britain Dec. 24, 1929 Great Britain June 2, 1932 Great Britain Dec. 19, 1938 

